Electromagnetic tracking may be provided in a number of medical applications. A path for a medical tool may be planed, the path may be overlaid over an image, and the medical tool may be tracked along the path. This tracking may be used for inserting a medical device (e.g., a needle) for biopsy or local treatment of a tumor. The tracking may be visualized using a volumetric pre-operation dataset such as a magnetic resonance (MR) dataset or a computed tomography (CT) dataset.
Electromagnetic tracking may also be provided for the guidance of intravascular devices such as, for example, catheters and guidewires. Pre-operation or intra-operation three dimensional (3D) images may be used as a 3D roadmap. An operator of the catheter, for example, may follow a planned path or a vessel along the 3D roadmap. The operator is to know where an actual position of the catheter is as the catheter is moved within the body of a patient. The actual position of the catheter may be obtained from one or more coils integrated into the catheter, for example. The one or more coils are tracked by an electromagnetic tracking system.
The electromagnetic tracking system knows a position of the one or more coils integrated into the catheter in a coordinate system of the electromagnetic tracking system (e.g., a world coordinate system). The electromagnetic tracking system, however, does not know the position of the one or more coils integrated into the catheter in a coordinate system (e.g., an image coordinate system) of a pre-operation scan (e.g., an MR dataset or a CT volumetric dataset) or an intra-operation scan (e.g., a 3D angiographic dataset or a DynaCT dataset).
If registration between the world coordinate system and the image coordinate system is achieved with a high enough degree of accuracy, and the morphological situation during an intervention does not change, the catheter, for example, may be moved forward in the body of the patient without any additional live imaging (e.g., fluoroscopy or ultrasound).
In one example in the prior art, registration between the world coordinate system and the image coordinate system is provided by fixing the mechanical relationship between an angiographic X-ray system and an Electromagnetic tracking system in combination with a calibration of the geometry of the angiographic X-ray system. In another example in the prior art, the registration between the world coordinate system and the image coordinate system is provided by a reference frame, which is visible in a volume of interest, including reference markers (e.g., fiducials) in a fixed relationship to a reference coil system.